The invention concerns a dental apparatus and more particularly concerns dental apparatus with an instrument holder having retractable hoses.
Apparatuses of this type are used for the performance of surgical and conservation treatment in dentistry. To this end, hand instruments must be supplied with operating materials such as water, air and electrical current by means of hoses and cables. The hoses used should therefore have a length which permits the removal of the instrument from its repository and its leading up to or into the mouth of the patient. On protective and hygienic grounds it is desirable to retract the hoses into the apparatus.
Various apparatuses of this type are known. One example is disclosed in German DP No. 836,833. In this, hose drums with expensive fittings are used while allowing the drum to turn to introduce the operating material into the hose. Spring loaded metal rings may be used to provide a seal against an escape of flow materials.
Another apparatus according to German DP No. 623,743 makes use of a flat spring in order to provide one or several round discs, with a moment of rotation in the direction of the coil winding of the hose. The discs are mounted so as to be turnable on an axis positioned in the middle section of the "housing". The end of the supply line which carries the tool, fits on the edge of the disc; the remaining supply line runs on the inner surface of the disc in the form of a flat spiral. This construction requires bearing material and an extra long hose for the disc, since the retractable end of the hose is wound on the outer edge and an additional hose section is found in the inner part of the disc which must have a sufficient length for the changing of its radius with the turning of the disc. In addition to one disc for each instrument, for each instrument a corresponding housing is also required. The disadvantage of this construction is to be seen in the expenditure of material and production costs.
An object of the invention is the task of avoiding in an instrument holder disadvantages of the expensive parts, such as a bearing journal for revolving discs in the form of spool drums, and feeder hoses with their problematic supplying of operating material with the operating material hoses, which often have a total length the multiple of their extension length.
Another object is to supply an advantageous control of the feed of the operating material for each individual instrument with consideration for a corresponding housing construction.